I read some knowledgebases to see it could be to do with permissions, so I've made sure the Admin Service is starting as the user that created the databases and also ensured that user has full rights to the database directory. Still the same.

Does anyone have any ideas?

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I think I've been through all the KB articles on it. I've set the admin service to use the account of the user that created the DB, I've also made sure that the user account has full access to the database folder.

When I cancel the connect attempt I finally get something in the logs.

[2017/12/06@12:14:46.974+0000] P-2132 T-2100 I BROKER 1: (8842) Could not spawn a SQL server.

Is your -Mn large enough to accommodate this new broker and its servers? If the servers table is full, the broker won't be able to spawn servers. Also: is -n large enough to allow for the new connections?

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